Anyhoo, sorry we can’t just stick to the technical drama.
Lower voltages help with power savings. Higher voltages can and do work better in high power, high noise environments though! 24V as you see is still very popular and useful inany applications.
Historical garbage and different manufacturing technologies. Be happy if you can get away with only 5V and 3V3 rails in your project. 24V is usually to interface with industrial sensors. And sometimes you see 12V as well, for stuff that's RS232 based.
And on top of that you got a fifth standard, 4..20 mA current loops. That one is used for long range transmission of analog values of a single sensor per wire pair, with 4-20 mA being seen as the value (4 mA = 0%, 20 mA = 100%), and anything less being seen as a cable break, anything higher as a short circuit somewhere.
4 to 20mA sensors are great. Invented in the 50s (!) to replace pneumatic controls and to this day work great. iirc they are usually 24V these days. You missed an important detail; the first 4mA (96mW) powers the sensor/local microcontroller (no local power supply required), and the remaining 4-20mA gives a calibrated current output for voltage/pressure/whatever you are measuring. If the output is less than 4mA or more than 20mA you know something is wrong (and many devices will output 20.1, 20.2 etc currents as a kind of fault code).
I'm guessing that the 2-10V is to detect line break conditions?
Yeah, it's a pain. Many of my boards have both 3.3 and 5 Volt rails. There are quite a number of level-shifting logic buffers, for instance that are powered by 3.3 but accept 5-V inputs with no penalty.
For hobbyist type stuff, a 3.3 V CMOS chip will accept a 5 V logic signal if you feed it through a series resistor, since the built-in protection diodes of the CMOS chip will clamp the voltage. Don't let the engineers catch you doing it. ;-) But I often use a series resistor to provide a little bit of overload protection to a CMOS input.
Little or no logic ever operated at 24 V, other than relays. There's always some level translation needed there. The higher voltage follows the same rule as electric transmission lines: Correspondingly lower current allows for thinner wire, of importance if you're driving something like a solenoid valve.
Then we had the 7400 series around then too, and boy howdy did that product line proliferate. The BJT TTL families got in so many things, but it demanded Vcc of 5V +-5% and I think it is safe to say anything expected to work with those chips standardized on 5V. Great, everyone is agre— ah.
74C is a CMOS line that happily uses 3V-15V. Ok, we can ignore that one it's just a... Nevermind, 74HC and friends do 2V-6V, neat. But it still works with the 5V so we're great.
So, CMOS got better, we got gates down to 3V or less with competitive propagation timing, and it turns out that less power use is good for clocking, but we can't actually feed anything 3V because of voltage drop so it's 10% higher cause... someone figured that was a nice round number or something? As for why it keeps dropping... Thinner conductor channels, thinner insulation, you do the math. Yes, power consumption with more gates is a reason too, but I'm pinning the biggest blame badge on decreasing sizes in the process nodes.
Oh, you know all that already and want to know about just the sensor/interconnect split? My bad. Line drop, afaik. 3.3V signalling is fine on a PCB or when your wires are short. Want to move your sensors further away? Maybe 5V will be a tad more reliable. That sensor over 20m away? Sure, 24V sounds appealing. I don't know the exact lengths where voltage drop on the wiring is enough to cause issues but I'm pretty sure that kind of reasoning in why it persists beyond simple logic compatibility.
As a secondary concern of the same form, non-differential protocols are voltages you have knowledge and control of, the various kinds of line noise less so. A data line offset by a volt is more problematic at 3.3V than 24V
Oh and if I'm driving a small industrial motor or actuator, or a 400V rated relay, I definitely want to be doing so with more enthusiasm than 5V signifies. I also want less enthusiasm than electrocution cause I touched a logic line. 24V will (just about) generally not give you a meaningful shock unless you try to lick it.
maybe someone from sparkfun could post advice for you here too...
Fwiw, I’m team adafruit on this. Hope it works out for y’all